The concept of flow originates from psychology [11]. Flow represents a holistic sensation that people feel when they act with total involvement [11]. Hoffman and Novak [24] noted that flow is characterized by: (1) a seamless sequence of responses facilitated by machine interactivity, (2) intrinsic enjoyment, (3) a loss of self-consciousness, and (4) self-reinforcement. Flow reflects a balance between users’ skills and challenges. When the skills exceed challenges, users feel bored. In contrast, when the challenges exceed skills, users feel anxious. If both skills and challenges are lower than the threshold values, users feel apathy. Only when both skills and challenges exceed the threshold values and have a good match will users experience flow.